Figure 4-2: The Path of Mars in 2016 From January 2016 through September 2016, Mars traverses zodiacal constellations from Virgo to Ophiuchus. Mars’s motion is direct (from west to east, or from right to left in this figure) most of the time but is retrograde (from east to west, or from left to right in this figure) during May to July 2016. Notice that the speed of Mars relative to the stars is not constant: The planet travels farther across the sky from January 1 to March 1 than it does from March 1 to May 1.